Furnace door



Sept. 20, 1966 G. J. NYBERG 3,273,521

FURNACE DOOR Filed Nov. 9, 1964 5 SheetsSheet 1 FIG.

GEORGE J. NYBERG INVENTOR.

p 2 1966 G. J. NYBERG 3,273,521

FURNACE DOOR Filed Nov. 9, 1964 5 Sheets-Sheet 2 67 FIG. 2

FIG. 3

I5 GEORGE J. NYBERG INVENTOR.

Sept. 20, 1966 G. J. NYBERG 3,273,521

FURNACE DOOR Filed NOV. 9, 1964 3 Sheets-Sheet 5 GEORGE J. NYBERG INVENTOR.

United States Patent 3,273,521 FUACE DOOR George J. Nyberg, Worcester, Mass, assignor to Riley Stoker Corporation, Worcester, Mass., a corporation of Massachusetts Filed Nov. 9, 1964, Ser. No. 409,690 6 Cllaims. (Cl. 11tl179) This invention relates to a furnace door, and more particularly, to apparatus arranged for viewing and having access to the interior of the furnace of a steam generating unit.

In the design and construction of a steam generating unit, it is necessary to provide in various parts of the unit, doors which serve to permit observation of furnace conditions. Such an observation door is shown in the patent application of Bruce and Parmakian, Serial Number 233,013, filed October 25, 1962; this observation window has a shutter which remains between the furnace and the observation window when it is not in use to prevent damage to the relatively delicate glass and its mounting. It is, however, sometimes necessary to provide such a window which is not only capable of permitting observation of furnace conditions but also to permit access. At that time, it is necessary to provide a gas pressure differential usually accomplished by means of air flow (particularly when a pressurized furnace is involved) to prevent a blast of hot gas from being emitted through the door when it is opened. Attempts in the past have been made to provide doors which were not only suitable for observation but also for access, but these doors have suffered from a number of deficiencies, not the least of which is their extreme complexity. In most cases, also, there has been no protection for the observation glass when the door was not in use. These and other differences in the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a furnace door capable of permitting observation of furnace conditions and also of opening for ac cess to the interior of the furnace.

Another object of this invention i the provision of a furnace door for observation and access which is simple in construction, which is inexpensive to manufacture, and which is capable of a long life of useful service.

A further object of the present invention is the provision of a furnace door using air flow to prevent a blast of furnace gas from being emitted from the door when it is open and having a simple and novel interlock between the air flow means and the door assuring that the air blast is present when the door is open.

It is another object of the instant invention to provide a furnace door having observation glass with a shutter to prevent damage to the glass and having means assuring that the shutter is open before the access door is open.

It is a further object of the invention to provide a furnace door having a protective shutter and an air flow means wherein an interlock is provided to assure that, when the door is opened, the air flow device is operating and the shutter is out of the way of the line of sight.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings in which:

FIG. 1 is a front elevational view of a furnace door embodying the principles of the present invention,

FIG. 2 is a bottom view of the door,

FIG. 3 is a side elevational view of the door, and

3,273,521 Patented Sept. 20, 1966 FIG. 4 is a sectional view of the invention taken on the line of IV-IV of FIG. 1.

Referring to the drawings, it can be seen that the furnace door, indicated generally by the reference numeral 10, consists of a housing 11 having an observation window 12 and a shutter 13 (see FIG. 4) with an actuating handle 14. The housing has a base ring 15 adapted to be mounted in a furnace wall to and provided with an inner ring 17 having a tubular portion 18 extending coaxially of the opening into the furnace and having an inner end which is engaged by the shutter 13. The base ring 15 is provided with a hollow abutment 19 into Which the shutter 13 is moved when it is desired to use the door. Mounted over the outside surface of the ring 15 is a circular plate 21 which is bolted to the ring 15; a seal 22 resides between the two members to hold them in gastight relationship. Similarly mounted on the outside of the plate 21 is a tube 23 which is bolted to the plate 21; a seal 24 resides between the two members. Extending radially inwardly from the inner surface of the tube 23 are two axially-spaced annular flanges 25 and 26, the inner edges of which are threaded. Threadedly mounted in these flanges is an orifice tube 27 having a number of nozzle passages 28 extending through the tube and inclined toward the axis and toward the furnace. The outer surface of the ring 27 and the facing surfaces of the flanges 25 and 2s combine with the inner surface of the tube 23 to form an annular air chamber 29 adapted to receive pressure air. The tube 27 is locked in its position of adjustment relative to the ring 23 by set screws 31.

The Window 12 is mounted on the outer end of the tube 23 and consists of a circular frame 32 in which is mounted glass 33, the inner surface of the frame being provided with a seal 34. One side of the frame 32 is provided with a hinge member 35 having two flanges 36 and 37 which embrace a similar pair of flanges 38 and 39 extending generally axially away from the outer surface of the tube 23. A pivot pin 41 extends through the flanges 33 and 39 and carries a screw 42 which passes through a bore 43 which extends through the hinge member 35. The outer end of the screw has a handle 44 threadedly mounted on it, the handle being prevented from leaving the screw by a lock nut 45. As is evident in the drawing, the screw 4-2 extends through the center of the pivot pin 41 and is locked to it. The flanges 36 and 37 closely embrace the outer surfaces of the flanges 38 and 3? but are not directly pivotally connected thereto.

Screwed into the ring 23 is a pipe fitting 46 which is connected by a conduit 47 to a ball valve 48, the other side of which is connected by a conduit. 49 to a source of pressure air (not shown) and to a guage 51 indicating air pressure. The valve 43 has an operating stem 52 extending vertically upwardly. Now, the handle 14 operating the shutter 13 is mounted on a shaft 53 which is torsionally biased by a coil spring 54- toward the position in which the shutter 13 covers the bore of the orifice tube 27 and the end of the tubular portion 13 of the inner ring 17. When the shutter is in this position, a pin 55 extends over the outer surface of the frame 32 of the window 12 to prevent the door from being opened. Mounted adjacent the handle 14 on the plate 12 is an abutment 56. On this abutment is slidably mounted a block 57. Guided in the block is an axially-slidable pin 58 which can serve to lock the handle 14 in the dotted position when the shutter 13 is recessed in the hollow abutment 19. This pin is slidable in the block and can be moved out of the way (as shown in FIG. 4) to permit the handle to be rotated back to its normal position. In addition, the block 57 carries a finger 59 which engages a notched washer 61 mounted on the shaft 53 and receiving the inner end of the coil spring 54. Various positions of rotation of the washer 61 produce an adjustment of the torsion of the spring 54 and this can be adjusted by using a wrench and using the finger 59 to lock the washer once a predetermined position has been reached. The block 57 and the abutment 56 are locked together by a pin 62 once the finger 59 has been placed between the teeth on the washer 61 to determine the washer position.

Extending from the left-hand side of the frame 32 of the window 12 are two spaced parallel latch fingers 63 and 64. As is evident in FIG. 2, the outer surfaces of these fingers are curved. The fingers overlie two parallel spaced flanges 65 and 68 formed as part of the ring 23. Extending between the flanges 65 and 66 is a tubular pivot pin 67 in which is mounted a screw 68 which extends between the fingers 63 and 64 and receives a threaded handle 69. A nut 71 is provided at the outer end of the screw 63 to assure tat the handle 69 is not removed. Mounted in the tubular shaft 67 and locked in place by a pin 72 is a vertical shaft 73 whose lower end is bifurcated and connected to the stem 52 of the ball valve 43 so that the stern moves with the pivot pin 67.

Extending laterally from the finger 64 is an abutment 74. This abutment overlies a latch member 75 which, in turn, consists of a block 76 from the bottom of which extends a latch 77. The block 76 has a bore 78 extending upwardly from its bottom. Axially in this bore is mounted a pin 79. Extending around the pin and pressing against a radial surface of the ring 23 is a coil spring 81, this spring tending to press the block 76 away from the ring 23 so that the latch 77 approaches the pivot pin 67. The pin 72 extends outwardly from the pivot pin 67 a considerable distance and a shoulder 82 is provided on the latch 77 to be engaged on occasion by the pin 72 to prevent the valve 48 from being closed while the window 12 is open. A sheet metal guide plate 83 is screwed to the outer surface of the ring 23 and serves as a cover and guide for the latch member 75.

The upper edge of the finger 63 is provided with a notch 84. Bolted to the adjacent side of the flange 65 is a sheet metal lock 85 which has a thin body residing in the notch 84 and an enlarged head extending on either side of the notch on the upper surface of the finger 63 to prevent the window from being opened by accident.

The operation of the apparatus will now be readily understood in view of the above description. The condition of the furnace door 10, when it is not being used, is shown in the drawings. In order to use it as an observation window, it is only necessary to rotate the handle 14 counter-clockwise to swing the shutter 13 up out of the way into the hollow recess 19. The handle 14 can be locked in this position by pulling the pin 58 outwardly so that, when the handle attempts to swing back under the torsional force of the spring 54, it will strike the pin 58 and it will be prevented from returning. If the spring 54 does not provide sufiicient return force to suit the operator, its tension can be adjusted by rotation of the washer 61. Before this can be done, however, it is necessary to remove the pin 62 so that the block 57 sides over the surface of the abutment 56 in an axial direction. When the block 57 has been moved axially, (either away from the furnace or toward it) the finger 59 no longer engages the notches in the washer 61, the washer can be rotated to a desired position. Then the finger 59 is returned to prevent the washer from rotating and the pin 62 is inserted again to lock the block 57 and the abutment 56 in this position. The glass 33 permits the observer to peer int-o the furnace through the internal bore of the orifice tube 27. If it is necessary to obtain access to the furnace to inspect or to use a soot blower or lance of some kind, it is necessary to open the window 12 by rotating it about the pivot pin 41. In order to do this, it is, first of all, necessary to loosen the handles 44 and 69; usually they are rotated until they come into contact with the nuts 45 and 71, respectively. Once the handle 44 has been loosened, it is possible to make use of the hinge member 45 rotative relative to the flanges 38 and 39 except for the various latching mechanisms at the left-hand side of the window. First of all, in order to have access to the furnace, it is necessary to move the shutter 13 into the recess in the abutment l9 and, for that purpose, the handle 14 is rotated in the same manner as is done when one merely wishes to observe. Once the handle 14 has been rotated and is locked in place by the pin 58, the pin 55 no longer resides over the frame 32 of the window, so that this impediment to the opening of the window has been removed. When the handle 69 has been loosened it is rotated over the surface of the fingers 63 and 64 so that the screw 68 is in a horizontal position. The movement of the handle in this way, of course, rotates the pivot pin 67 which, in turn, rotates the shaft 73 and the stem 52 of the valve 48. The valve is, therefore, opened and air passes from the conduit 49 through the valve 48 through the conduit 4-7 and the fitting 46 into the chamber 29 in the window. After passing into the chamber 29 the air then passes through the nozzle passages 28 and is directed toward the furnace. This produces a fiow of air which prevents pressure air from the furnace proper into moving out through the window. Once the handle 69 and the screw 68 are in the laterally-extending position, it is only necessary to move the upper end of the latch 85 upwardly so that it is free of the finger 63 and the notch 84. When this is done, it is possible to rotate the window about the hinge pin 41 to its open position, in which position access is had to the furnace. As the window moves away from the rest of the furnace door, the finger 74 lifts from the upper end of the latch member 85, more specifically, from the top of the block 76. The spring 81, therefore, acts to push the block 76 away from the flange of the ring 23 and carries the latch 77 closer to the pivot pin 67. The pin 72, when the valve 48 is open, occupies a position directed downwardly 90 from the position shown in FIG. 2; it therefore, strikes against the shoulder 82 on the latch 77 and it is not possible to rotate the shaft 73 to close the valve while in this position. It should be noted that a web 86 (see FIG. 2) limits the downward motion of the handle 69 and the screw 68 so that it is not possible to close the valve 48 by rotating the handle further in the counter-clockwise direction. This situation assures that, as long as the window is open, it is not possible to close the valve and accidentally prevent air from flowing through the door into the furnace.

Finally, when the operator is through using the door for access, he swings the window back into place. The finger 63 strikes an inclined surface of the latch 85 to move it upwardly; it then snaps back into place in a notch in the finger 63. The movement of the window in this way brings the finger 74 into contact with the block 76 of the latching member and pushes it inwardly, carrying the latch 77 away from the pin 72, so that it is possible to rotate the handle 69 and the screw 68 upwardly into its original position. The top edge of the latch is bent upwardly so that, when the top edge of the finger 63 strikes it, it is cammed away from the finger and then snaps back into the notch 35 once the finger has passed the enlarged head of the latch. With the window back in place, the handles 69 and 44 are tightened up to cause the seal 34 to press tightly against the back surface of the frame 32 to provide a gastight operation. The rotation of the handle 69 back to its original place has caused a closure of the valve 48 so that air no longer flows to the frame. Then the pin 58 is moved axially away from the handle 14 and the spring 54 returns the handle to its original position so the shutter 13 comes down into position to shield the window.

It can be seen, then, that one cannot open the window 12 without supplying air to the nozzle passages 28. Furthermore, one cannot open the window without rotating the handle 14 and causing the shutter 13 to move into its recessed position. In addition, the latch 85 assures that the window must be deliberately opened and that, even though all other conditions permit the window to be open,

the operator must thoughtfully decide that he wishes the Window open and must move the latch upwardly in order to release the window and permit it to be swung entirely open. At the same time, it is clear that the air cannot be shut off as long as the window is open. An inspection of the fingers 63 and 64 will show that they are considerably longer than is necessary merely to act as part of the latching mechanism; this length makes it necessary to rotate the handle more than 90 before the Window is free to open, so that the valve is completely open before the Window is free.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, What is claimed as new and desired to secure by Letters Patent is:

1. A furnace door, comprising (a) a housing adapted to be mounted on a furnace wall,

(b) a transparent window hingedly mounted on the housing,

(c) a shutter mounted in the housing and movable from a first position in which it lies between the window and the interior of the furnace and a second position in which it does not so lie,

(d) apparatus operative, on occasion, for causing a flow of air through the housing into the furnace,

(e) means preventing the opening of the window unless the said apparatus is operative and unless the shutter is in the said second position.

2. A furnace door as recited in claim ll, wherein means is provided to prevent the said apparatus from becoming inoperative as long as the window is open.

3. A furnace door as recited in claim 1, wherein means is provided to assure that the said apparatus is entirely operative a short period of time before it is possible to open the window.

4. A furnace door as recited in claim 3, wherein the last-named means consists of a pair of parallel fingers and a handle rotatable between them from a locking position to a free position of the window, the rotation of the handle operating the said apparatus, the parallel fingers being extremely long, so that the apparatus is completely operative before the handle reaches the free position.

5. A furnace door, comprising (a) a housing adapted to be attached to a furnace wall,

(b) a hinged window mounted on the housing,

(0) an air flow apparatus including a shut-off valve,

(d) a lock normally holding the window in closed position and movable to release the window, the lock including a handle which is mounted on a pivot pin, the pivot pin rotating with movement of the handle and connected to the valve for the operation thereof to open the valve when the lock is moved to release the window, and

(e) means preventing movement of the lock to close the valve while the window is open.

6. A furnace door as recited in claim 5, wherein the valve is of the ball type having a stern Whose rotation moves the ball from open to closed position, and wherein the pivot pin is directly connected to the valve stem so that they partake of the same rotation.

References Cited by the Examiner UNITED STATES PATENTS 2,528,671 11/1950 Selnick l10-l79 KENNETH W. SPRAGUE, Primary Examiner. 

1. A FURNACE DOOR, COMPRISING (A) A HOUSING ADAPTED TO BE MOUNTED ON A FURNACE WALL, (B) A TRANSPARENT WINDOW HINGEDLY MOUNTED ON THE HOUSING, (C) A SHUTTER MOUNTED IN THE HOUSING AND MOVABLE FROM A FIRST POSITION IN WHICH IT LIES BETWEEN THE WINDOW AND THE INTERIOR OF THE FURNACE AND A SECOND POSITION IN WHICH IT DOES NOT SO LIE, (D) APPARATUS OPERATIVE, ON OCCASION, FOR CAUSING A FLOW OF AIR THROUGH THE HOUSING INTO THE FURNACE, 